(CNN) — Iowa Republican Sen. Joni Ernst has decided not to seek reelection to a third term, two people familiar with the decision say, and is poised to make an announcement next week.

Ernst, 55, has been wrestling with the decision for months, but began telling friends in recent days.

Her retirement creates an open Senate seat in Iowa. Rep. Ashley Hinson is making plans to jump into the race, one GOP official says. National Republicans, anticipating Ernst’s retirement, have long said they believe Hinson would be a strong candidate.

A crowded field of Democrats is already running. The party’s primary field includes state Rep. Josh Turek, a Paralympian wheelchair basketball player, state Sen. Zach Wahls, Knoxville Chamber of Commerce executive director Nathan Sage and Des Moines School B

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